Time series graphs show data over a time period. The time period is always shown on the $$x$$-axis. Data points are joined chronologically by line segments.

Extrapolation is the process of estimating unknown values that are outside the range of existing data.

Interpolation is the process of estimating unknown values that are inside the range of existing data.

Interpreting and drawing real-life graphs

Maths

The work on gradient in the prior unit is expanded further in this unit by considering gradient as the rate of change and interpreting this in context. The gradient of the tangent is introduced as a way of estimating the gradient of a curve.

Real-life graphs

On a time series graph, data points are joined chronologically by __________.

We do not know if the trend continues in the future.

We do not know if the data points are plotted accurately.

We do not know how the data changes between the data points. 

We do not know if the scale is consistent between the coordinates. 

Why can it be inaccurate to interpolate from a time series graph?

Which graph would match Andeep's scenario?

This container is filled at a constant rate. Which graph could model this scenario?

This container is filled at a constant rate. Which graphs could model this scenario?

Water was run at a constant rate throughout.

Water was run at a continuously increasing rate .

Water was run at a constant rate then the rate was decreased continuously.

Water was run at a constant rate then the rate was increased continuously.

Aisha is filling this container with water. What must be the case for this depth-time graph to be accurate?

__________ is the process of estimating unknown values that are outside the range of existing data.

__________ is the process of estimating unknown values that are inside the range of existing data.

This is the cross section of a container. If it was filled at a constant rate, which of these would be its depth-time graph?

This is the cross-section of a container. If it was filled at a constant rate, which of these would be its depth-time graph?

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Interpreting and drawing real-life graphs

Lesson outcome